The present invention relates to centrifugal sprayers, and more particularly to centrifugal sprayers having a motor driven disc element fixedly attached to a liquid feed element, wherein the liquid feed element is attached to the disc and is suspended and immersed into a supply of liquid to be sprayed.
U.S. Pat. No. 4,294,408, issued Oct. 13, 1981, shows a centrifugal sprayer of the type generally related to the present invention. In this type of sprayer a rotating disc is suspended over a supply of liquid to be sprayed, and a feed mechanism is connected to pump liquid up to the spinning surface of the disc where it is centrifugally hurled outwardly in atomized form through a variable gate, to be deposited upon a surface. The aforementioned patent shows a feed mechanism comprising a screw pump, wherein the screw is contained within a tube in immersion in the liquid to be sprayed, and is direct-coupled to the drive mechanism which rotates the disc, so that as the disc is rotated the screw pump also rotates, thereby conveying liquid upwardly and into contact with the spinning surface of the disc. The screw pump mechanism performs adequately for some types of liquids and under certain conditions, but does suffer from a number of disadvantages. Among these disadvantages is the screw, while being immersed in the liquid to be pumped, causes continual agitation of the liquid with resulting aeration of the liquid, which reduces the pumping flow rate of the mechanism. Further, the screw pump is quite difficult to clean, especially when liquids such as paints are being sprayed by the device.
U.S. Pat. No. 3,668,996, issued June 13, 1972, shows a centrifugal atomizer having a rotatable hollow cone immersed in liquid, and connected to a disc for feeding liquid onto the disc for atomization. The cone and disc are formed from a single part, and are attachable to the shaft of a drive motor for uniform rotation. This construction suffers from the disadvantage of being difficult to clean, and from the further disadvantage of rotational instability at high rotational speeds, particularly when high viscosity liquids are sprayed. The cone is supported along an annular line at a point proximate the top of the cone, and high rotational speeds can cause instability of the cone as it is immersed in liquid.
U.S. patent application Ser. No. 565,400, filed Dec. 27, 1983, and owned by the same assignee as the present invention, shows a centrifugal sprayer having a motor driven disc and cone feed mechanism, wherein at least several different cone angles may be utilized for the feed mechanism in interchangeable relationship. It includes an outer housing which performs the multiple functions of collecting excess liquid and draining back to the liquid reservoir in which the cone is immersed, preventing the formation of a liquid vortex at the bottom of the cone feed mechanism, and providing a supporting bushing surface for guiding the cone in stable rotational operation. The disc and outer housing are constructed so as to enable the use of interchangeable cone feed members, wherein different cone angles may be incorporated to better control the pigment separation of different liquids.